The general rationale behind this project is that circadian rhythm distrubances play important roles in sleep disorders such as those involving complaints of insomnia and hypersomnia. In the first year, previous data were analyzed and reported results showed that mice can present a disrupted wakefulness-sleep cycle (electrographically defined) in conjuction with a clear activity-inactivity cycle (defined by wheel running). We have developed a computer based system to automatically monitor mice to further elucidate causal factors in such rhythm dissociations. BIBLIOGRAPHIC REFERENCES: Glen, L., Lewis, D., Mitler, M. and Dement, W. Behavioral observation versus polygraphic recording in the mouse. Evaluation of sleep scoring errors. Sleep Research 4:144, 1975. Mitler, M., Sokolove, P., Lund, R., Pittendrigh, C. and Dement, W. Activity-inactivity and wakefulness-sleep in mice: induced changes in cyclic relationships by prolonged exposure to constant conditions. Sleep Research 4:267, 1975.